1. Field of the Invention
The present invention relates to a computer system, and more particularly to an apparatus and method of interfacing video information in a computer system.
2. Background of the Related Art
A related art computer system, as shown in FIG. 1, includes a main body 1, such as a personal computer (PC) or a work station. The main body 1 performs various kinds of information operations and information processing, and generates a video signal for displaying corresponding processed contents on a display screen. A monitor 2 receives horizontal and vertical sync signals H-sync/V-sync and a RGB video signal outputted from the main body 1, as shown in FIG. 2. The monitor thus displays a corresponding image, and performs various kinds of information interface with the main body 1 through serial data (SDA) and serial clock (SCL) lines of a display data channel (DDC).
The monitor 2 comprises a microcomputer 11 for detecting the display type of an input video signal by analyzing frequency information of the horizontal and vertical sync signals. The monitor 2 outputs a control signal so that the RGB video signal transmitted from the main body 1 is processed using the same format as the corresponding display format, or in a form that corresponds to the closest factory mode. The monitor 2 further includes a video processing section 12 for processing the RGB video signal transmitted from the main body 1, to match the corresponding display type in accordance with the control signal from the microcomputer 11. Finally, a display section 13 displays an output of the video processing section on the display screen.
The operation of the related art computer system as constructed above will be described. First, the main body 1 of the computer system transmits the horizontal and vertical sync signals, as well as the RGB video signal to the monitor 2.
The microcomputer 11 in the monitor 2 detects the type of the input video signal in accordance with the frequencies of the horizontal and vertical sync signals, and controls the video processing section 12. This allows the input video signal to be displayed in a factory mode which is closest to the video type among factory modes predetermined in the monitor 2. The video processing section 12 processes the input video signal to match the factory type determined by the microcomputer 11, and displays the input video signal through the display section.
In the case of an analog type cathode ray tube (CRT) monitor, the factory mode corresponds to a table of the image type corresponding to the frequency information of the horizontal and vertical sync signals. Specifically, that includes an active video frequency for one horizontal period, a backporch time for one horizontal period, the total number of horizontal lines for one vertical period, and a backporch time for one vertical period, among others.
For a digital type liquid crystal display (LCD) monitor, the factory mode corresponds to a table of the image type corresponding to the frequency information of the horizontal and vertical sync signals. Specifically, that includes the total number of dots for one horizontal period, the number of backporches for one horizontal period, the total number of horizontal lines for one vertical period, and the number of backporches for one vertical period, among others.
The main body 1 transmits only the RGB video signal and the horizontal and vertical sync signals to the monitor 2. This, however, is not enough for the monitor 2 to detect the type of the video signal transmitted from the main body 1. In order to actually display the video signal, such as the above-described video type, information regarding the active video frequency for one horizontal period and the like is required.
Accordingly, the factory mode, which has the video types corresponding to the representative horizontal and vertical sync signal frequencies listed in table, is applied to the respective monitor 2. The frequency of the horizontal and vertical sync signals transmitted from the main body 1 is compared with the frequency of the horizontal and vertical sync signals of the predetermined factory mode, and if the same horizontal and vertical sync signal frequency exists, the video signal is displayed using the video type corresponding to the horizontal and vertical sync signal frequency.
If, on the other hand, the same horizontal and vertical sync signal frequency does not exist in the table, the video signal is displayed using the video type corresponding to the frequency closest to the frequency of the horizontal and vertical sync signals transmitted from the main body 1.
Thus, according to the related art computer system, if the frequency of the horizontal and vertical sync signals transmitted from the main body does not coincide with that of the predetermined factory mode in the monitor, the position or size of the displayed picture will become abnormal, and a normal picture desired by the user cannot be outputted.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.